Finned tube



Jan 9, 1951 c. s'. slMPx-:LAAR 2,537,797

FINNED TUBE Filed Aug. 8, 1946 3 Sheets-Sheet l Jan. 9, 19541 c. s. slMPELAAR 2,537,797

FINNED TUBE 3 Sheets-Sheet 2 Filed Aug. 8, 1946 Jan. 9, 1951 c. s. slMPELAAR FINNED TUBE Filed Aug. 8, 194e 5 Sheets-Sheet 5 -UN1rsn- STAT 4its wall.'

Patented Jan. 9, 1951 FINNED TUBE Clyde S. Simpelaar, Racine, Wis., AModine Manufacturing Company,

assigner to Racine, Wis.,

a lcorporation of Wisconsin Application vAugust s, 1946, serial No. 689,092

- This invention relates to` tubular finned heat exchange elements, and its principal object is to provide auid conducting tube with integrally formed fins, either Aprojecting inwardly from its `tubewall or projectingoutwardly therefrom, or

projecting -both Ainwardly and outwardly from Various means have heretofore been used to provide tubes with finned surfaces. The principal objection to previous`y made flnned tubes-is -the cost of the basic tube on which fins of separate materialare added, or expensive tubes, which 9 ciaims. (c1. asv-262.14)

Fig. 2 is an end elevation thereof, looking in the direction of the arrow 2 in"Fig. 1;

are further formed or worked to provide extended surfaces.

Another` object is to provide a finned tube composed of a metal strip wound helically upon itself intoa tubular form, and having ns struck up `therefrom along the length of the portion thereof which -is disposed at least on one side of its median line, and having an imperforate overlapping portion covering the perforations left by the struck up fins, and the contacting faces of the convolutions being brazed, solderedor otherwise bonded together to provide an imperforate tube having ns projecting from its inner .or outer face, or from both faces.

Tubes embodying the present invention are applicabeto practically any type of heat exchangers. The tubes represent in themselves a combination of tube, inside ns, outside fins and headers, when the ends thereof are of a form having hexagonal or other polygonal shaped ends which, when nested, and joined by a welding or brazing process, may constitute a complete core assembly.

Particular applications of the present tube would be forheat exchangers when heat transfer coeiiicient of fluid inside of the tube or tubes is controlling, and a substantial increase in the overall heat transfer coeicient can be obtained by increasing the surface and fluid turbulence onv the side which is contro'ling. Other specific typesof applications would be hot gas fiues in boilers and hot water heaters, jacketed exhaust stacks for heat recovery, etc., counter flow gas to gas heat exchangers.

Withthese and other objects and advantages in view, this invention consists in the several novel features hereinafter fully set forth, and more 'paticularly defined in the appended claims.

The invention is clearly illustrated in the drawings accompanying this specification; in which Fig.1 is a side elevation of a partially formed tube embodying one form of the present invention;

-another form of 11n;

Fign3` is of Fig. 1;

Fig. '4 is a fragmentary lhorizontal section through the wall of the tube taken on the line 4-4 of Fig. 1;

` Fig. 5 is a similarrsection of a slightly modified form of the invention; t Fig. 6 is a similar section of a second modificaion;

Fig. 7 is an elevation y seen in Fig. 1, nested and bonded together to form a radiator core;

Fig. 8 is a fragmental perspective .view of a a cross-section taken on the line tube strip illustrating one form of fin;v

Fig. 9 is a fragmental perspective view illustrating another form of fin;

Fig. 10 isa fragmental perspective view of still Fig. 11 is a side elevation of a partially completed tube embodying another modied form of the invention;

Fig. 12 is a cross-section taken on the line |2-I2 of Fig. 11;

Fig. 13 is a side elevation of a partially coinpleted tube illustrating another modiiied form of the invention;

Fig. 14 is an end view of 13, looking Fig. 13;

Fig. 15 is a detail horizontal section through the wall of the tube seen in Fig. 13, taken on the line I5-I5 of Fig. 13;

Fig. 16 is a side elevation of a partially formed tube embodying still another modied form of the invention;

Fig. 1'7 is a front elevation of an automobile radiator, of which the core is composed of tubes embodying the form of tube illustrated in Figs. 1 and 7;

Fig. 18 is a detail horizontal fragmentalsection taken on the line lli-I8 of Fig. 17, with one of the tubes partially broken out and others shown partially in dotted lines;4 Y

Fig. 19 is an end elevation of a group of finned tubes embodying the present invention, and' provided with external extended finned surfaces; and i Fig. 20 is a side elevational view of the structure illustrated in Fig. 19.

Referring to said drawings, and tiret to Figs. 1

the tube seen in Fig. in the direction of the arrow I4 in to 4 inclusive, the tube shown therein is formed of a metal strip 20 wound helically uponitself to form a. tube 2|. Themetal strip is struck up of a number of the tubes 3 with suitable dies to form fins 22 that occupy substantially one-half of the width of the metal strip. These ns may take any of several forms. and the metal strip may be wound upon itself to bring the iins on the internal side of the tube, or the metal strip may be wound so as to bring the fins on the external side of the tube wall, as is seen in Figs. 1l and 12.

The fins may be omitted from the end portions of the strip andthe end portions of the tube may be expanded outwardly to provide walls 23 of many sided configurations such. for instance. as hexagonal or other polygonal configurations, whereby the tubes may be assembled, as seen in Fig. 7, with the fiat faces of each tube contacting with other hat faces of other tubes. and bonded together to form the core of a radiator, as is well understood.

In winding the strip upon itself, the imperiorate part thereof may overlie the nned perforated part of the next adjacent convolution, thereby causing the apertures which are formed as a result of striking up the fins from the metal strip to be covered. The metal strip may comprise a strip straight in cross-section. as shown in Fig. 4, and a plain lap joint may be made between contiguous convolutions. However, the metal strip may be preformed by offsetting the strip longitudinally thereof midway between its side edges. as is seen in Fig. 5. When the preformed strip, as shown in Fig. 5 is used, a cylindrical tube results therefrom. In either case, it is to be understood that the overlapping contiguous convolutions of the tubes are brazed, soldered or otherwise bonded together.

In Fig. 6 is shown a slight modification of the present invention. In this form of tube. the metal finned strip 24 is wound helically and the convolutions are butt joined. This metal strip is formed with the ilns as in other forms. A second strip 26 is wound helically upon itself in contact with the strip 2l and is bonded thereto. The strip 26 is imperforate and serves to close the apertures formed in the ilnned strip.

Fig. 8 shows a fragment of a metal strip 20, struck up with suitable dies to form square or rectangular hns 22; Fig. 9 illustrates a metal strip 20 struck up with suitable dies to form a fin 22b of triangular form, and Fig. 10 illustrates a metal strip 2li struck up with suitable dies to form a semi-circle fin 22. Obviously, the fins may be given any desirable shape best suited for the particular purpose intended. and may be formed by scariing the strip without piercing the strip.

Figs. 11 and 12 illustrate a modined form of the invention, wherein the fins 22d are disposed on the external side of the tube. The fins are struck up along the strip at one side of its median line as before. but the metal strip is wound on .itself` to leave the fins disposed on the external side of the wall formed by the wound strip, the apertures left by the iln's being covered by the imperforate part of the strip by the next adjacent convolution, which `in this case is on the inner side of the tube wall.

In the modified form of the invention, illustrated in Figs. 13 and 14, fins 22 are disposed on the inner face of the tube wall, and other ns 22t are disposed on the outer face of the tube wall. In this case, the metal strip 20h is struck up with suitable dies to form rows of iins 22L at one side of the median line of the strip, that extend in one direction from the strip, and other rows of fins 22f are struck up at the other side of the median line of the strip and extend in the opposite direction from the strip. Between the two rows of ilus, the strip is left imperforate. This metal strip is wound upon itself so that the imperforate part of the strip covers the apertures left by the dns along the inside of the tube wall, and also covers the apertures left by the iins on the outside of the tube wall, so that all of the apertures are covered by the imperforate part of the strip (see Fig. 15).

From the above it is clear that the double walled impcrforate tube is formed having inwardly and outwardly projecting fins extending from the wall thereof.

Obviously, the iins can be struck up from the metal strip to stand in planes parallel with the axis of the tubes, or they may stand at right angles thereto, or at any other suitable angle to the axis of the plane.

In the previously described form of the fins. the metal strip is wound externally of the tube. Fig. 16 shows a modification of the invention in which the metal strip 201 is wound internally of the tube. The metal strip may be offset as in the form of a metal strip illustrated in Fig. 5. and the ns 221 project inwardly from the tube wall formed by the helically wound strip.

Fig. 17 illustrates an application of a finned tube to the core of an automobile radiator 21. Finned tubes having hexagonal ends 23 are nested together with the ilat faces of the end portions bonded together, and the endmost tubes bonded to the walls 28 of the radiator,` structure.

In Figs. 19 and 20 several of the finned tubes are illustrated, to which is applied extended iin members 29 of common construction bonded to the finned tubes. This arrangement provides a core for many types of heat exchangers.

In each form of the invention above described, the metal strip may be pre-formed and wound upon itself by automatic machinery, which forms no part of this invention, and the bonding may take place as the strip is being wound. Since the tube, when fabricated becomes a solid tube; that is, there are no perforations not covered by solid metal, it may be cut at any point. As a convenience, the strip may be wound into a tube of indeiinite length, and may be subsequently cut up into desired lengths. The ends may be left square, as shown in Figs. 13 and 16. and bonded to suitable headers, or they may be expanded into hexagonal or other polygonal forms as required.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same Without departing from the spirit of my invention; hence I do not wish to be 'understood as limiting myself to the exact form,

construction, arrangement and combination of parts herein shown and described or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. A iinned tube, comprising a wound metal strip having helical overlapping bonded together convolutions, said strip having an imperiorate section extending along its length at one side of its median line, the section of the strip on the other side of the median line having fins struck up therefrom inwardly of the edges of the strip, which leave apertures in the strip initially occupied by said iins and the imperiorate section of the strip covering said apertures.

2. A finned tube, comprising a wound metal strip having a longitudinally extending, lateral and being periorate nd ansvers extent at u least equaltothe ans erse x alongt nr occu mentioned edge d perora e pa tial onded severa oi t fl str in rolled with h the imo t e imp riorat ge ion of the sa e coverppc ing the c pposite iin carrying porng th tion of the 8. d t b com rising etal strip hav metal ing a longit din ily e tendin perf ra sec together w tion, port of he s id l t ra acent riorate to said section having t c th reiroin way be and extending ou war tr nsverse thereto, the strip planes of the respecti e ns e t nd ans ck up versely the edg s of s str leaving i tially ope t e trip i ially p d by such riorate seca ing l cally n overlapsaid apertures. ping, bonded together convolutions, with the iinstrip perforate section of the strip covering said opens. e another 9. Externally and internally nnned tubing conile thick prising a longitu xtendin o tal rtions o having ong t lo gitudina dge portions oi the plies oi ube of the sa part ally red oi the initially plane o h str d leavin s along terial forming the said edge portions o1 the strip, the fins along one s edge por i n be disp e sid metal strip havstrip, and the fins along the other edge portion i perfo a ec` g disposed oppo ite d e strip, t ip latera adi cent the intermediat oi the s rip being thereirom perorate Aand oi a transverse extent at least h leave ual o the ans x n h 'edges d y said periorate y h p tia of the d, verlap nns, said strip be' i h p rforate. ti ns, the termediate p tion o ring vering said openings in the fin carrying portions of the saine.

, CLYDE SIMPELAAR. metal strip havi ,f mperiora' Sec- REFERENCES CITED ent The following references e ecord in the s lthreffffgt 40 nie or this patent: a verse e e o,

tend M UNI STATES PA trip, leav- Number Name Date cupied by 1,363,416 Hooker 28, 1920 und, over- 1,113,020 Bowne May 14, 1929 l tions, wi h the 1,134,13 Kram Nov 5, 1929 t ip said 1,136,906 Flinterm nn Nov 1929 1,111,182 Bundy 1, 1930 ising a iudinally 1,853,315 1 Medine Apr 12, 1932 long one 149,696 Holm Mar 1, 1939 the a e pa ially 2,345,331 Dono e al Mar. 29. 9&4 plane t e strip 2,312,195 Rodeck Apr 1941 long said rtion o 2.336,15 Elder Oct 2. 94 

